William h



W. H. BRISTOL THERMO ELECTRIC COUPLE.

APPLICATION FILED AUG.14, 191B.

- WILLIAM H, BRISTOL, 0F WATERBURY, CONNECTICUT, ASSIGNOR TO THE BRIS'I'QL' COMPANY, OF 'WATEBBURY, CONNECTICUT, A CORPORATION OF CONNECTICUT.

THERMO-ELECTBIC COUP" Specification of Letters Patent. Patsgntgd Sept, 9, 191,9

Application filed August rte-191s. Serial in. 249,772

The invention relates to thermoelectric couples, more particularly of the compound type as set forth in my prior U. 6. Letters Patent No. 764177,,of July 5th, 190%, said couples consisting of an active or lire end portion and an extension portion, the latter forming at the junctions With the former secondary couples Whose thermoelectric effects under variations of temperature are arranged to neutralize each other.

This patent discloses more particularly the use of expensive andliighresistance elements such as platinum and a platinum alloy for the primary couple; and it is the object of the present invention to provide a compound couple of Which also the primary portion shall he composed of comparatively inexpensive base metal elements and the extension portion of inexpensive base metal elements, generally of not particularlyhigh melting point and of comparatively low resistance, whereby said latter elements need not be of large cross-section and will possess sutlicient flexibility to be conveniently bent and carried considerable distances. In the construction of couples of this character, diliiculty has been experienced in obtaining uniformity in the manufacture of some of the alloys employed therein; and it is the particular ob ject of the present invention to afiord such a combination that the-particular alloys composing the elements thereof shall be comparatively inexpensive and be readily manufactured Within the commercial limits of uniformity. The novel combination permits, also, of ready correction due to any slight departure from standard proportions of the metals composing the two extension portions.

A further object of the invention is to combine such elements in a compound couple that a particularly high electro-motive force may be developed and of a comparatively straight line electro-motive force-temperatu e curve. Moreover, it will generally be desirable to have the elements of the prinickel-aluminum, etc. is particularly suitable for the primary con-' mary couple of metals of comparatively high melting, point, While the metals of theexteir.

sion portion maybe of a lower melting point, not, as a rule, being exposed to extreme temperatures.

The drawing illustrates, diagrammatically, the improved compound couple. 4

As elements for the primary couples v arious metals, or alloys, are suitable, for ,examplenickel, tungsten, nickel chromium, A combination that plc is that set forth in U. S. Patent No. 971767, granted Oct. 4", 191cm) Albert L. Marsh, the same consisting of a nickel-chr0- inium alloy (10% Cr.) as one element and a nickelahiminuni alloy (aluminum approximately 2%) as the other element. Such couple will give a practically straight-line elcctromotive force-temperature curve to substantially the working limit of the material. I have found that it is advantageous to make both of the elements of the extension portion of the couple of alloys of copper and nickel, one element being alloyed With from 29% to 60% of thelatter metal, and the other with a small amount of the said nickel, for example less than 1% thereof, the proportion of alloying metal being determined by the neutralizing efi'ect required. With the particular primary couple hereinbefore set forth and'composed of elements of nickel with approximately ten per cent. (10%) of chromium and of nickel with approximately two per cent. (2%) of aluminum, particularly satisfactory results may be obtained by employing for the extension portion copper alloyed with approximately one-half of one ercent. (e70) of nickel in combination with the nickel chromium element, and copper H with approximately forty per cent (40%) of nickel in combination with the nickelaluminum element of said primary couple, as shown in the drawing. 1th thls combination, an electro-motive force is deve1- v oped which 13 from four to five times that of the platinum-rhodium couple. The junctions between the primary portion and extension portion of the couple, also, may be exposed to comparatively high temperatures p 105.

The fact that the said extension flexibility, permits, moreover. of this portion of the couple being conveniently extended even to considerable distances. The cold end of the cogple may thus be removed. to

some remote ,point here the temperature.

is substantially uniform, or readily maintained so, and thereby errors of inoiicetion from fluctuations of temperature the mid. cold end/be/Uobviated.

I claim;

1. A eonipound. thermo-elect *ic eouyle con-- sisting of a primary portion, one part of which 'isfen alloy containing nickel. and relatively small proportion of alumiimm. and the other a nickel-chromiun1 a iioy an extension portion, one part of which is copper alloyed with a small amount and. less than one (1%) per cent. of niche the some being *combined the niekel ehrozniuzn part of the pnmary portlon, and the other "an alloy of copper and nickel-and. combined.

' pl-im my pt 'sisting of primary of the said? 2. Aco-mpouno thermoelectric couple conportion, one part of nickel and z pwhioh is, am containing prommetely 2min, ems. the other am alloy containing nickel and. i'ippyoximat ly ten {10%) per cent. of.

BRISTOL.

two {51%) per cent. of alumt 

